/*
 * Copyright 2011-2013 HTTL Team.
 *  
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *  
 *      http://www.apache.org/licenses/LICENSE-2.0
 *  
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package httl.spi.filters;

import httl.spi.Filter;
import httl.util.Reqiured;
import httl.util.StringUtils;

/**
 * CommentSyntaxFilter. (SPI, Singleton, ThreadSafe)
 *
 * @author Liang Fei (liangfei0201 AT gmail DOT com)
 * @see httl.spi.translators.CompiledTranslator#setTextFilter(Filter)
 * @see httl.spi.translators.InterpretedTranslator#setTextFilter(Filter)
 */
public class CommentSyntaxFilter extends AbstractFilter {

    private String commentLeft;

    private String commentRight;

    private boolean removeDirectiveBlankLine;

    /**
     * httl.properties: comment.left=&lt;!--
     */
    @Reqiured
    public void setCommentLeft(String commentLeft) {
        this.commentLeft = commentLeft;
    }

    /**
     * httl.properties: comment.right=--&gt;
     */
    @Reqiured
    public void setCommentRight(String commentRight) {
        this.commentRight = commentRight;
    }

    /**
     * httl.properties: remove.directive.blank.line=true
     */
    public void setRemoveDirectiveBlankLine(boolean removeDirectiveBlankLine) {
        this.removeDirectiveBlankLine = removeDirectiveBlankLine;
    }

    public String filter(String key, String value) {
        boolean left = false;
        boolean right = false;
        String trim = value.trim();
        if (trim.startsWith(commentRight)) {
            value = value.substring(value.indexOf(commentRight) + commentRight.length());
            left = true;
        }
        if (trim.endsWith(commentLeft)) {
            value = value.substring(0, value.lastIndexOf(commentLeft));
            right = true;
        }
        if (removeDirectiveBlankLine && (left || right)) {
            value = StringUtils.trimBlankLine(value, left, right);
        }
        return value;
    }

}